This relates in general to lock-controlled switches for electrically operated doors, more particularly, to lock-controlled switches for use on electrically operated upward acting doors of the types used in garages and warehouses.
Large numbers of garage doors and warehouse doors are equipped in the present state of the art to be opened and closed by an electrical operator in response to remotely-controlled signals. When such operators are installed on doors, the locks on those doors are often either removed or disabled. This renders the door more accessible to a forced entry. If the locks are left operable the guarantee is cancelled by the installation company. For this reason, many insurance companies insist that such remotely-controlled electrically operated doors be locked manually in order to avoid the possibility of the doors being forced open by burglars and other unauthorized persons. Since it is difficult for one using an electrical operator responsive to remotely-controlled signals to determine whether or not a door has been manually locked, every year millions of dollars worth of damage is done because doors are locked, and the locks, sections, and tracks are damaged when the electrical operator is remotely engaged.
Although several lock-out switches are available in the prior art for disabling electrical operators for opening and closing garage doors, they are complex and expensive to produce and install. Furthermore, many of the available prior art switches of this type have several operational disadvantages. For example, in many such switches, there is a dead point at which the lock is engaged, but the electrical operator is still operational. A further disadvantage which is characteristic of most types of such prior art switches is that the `throw` of the switch is limited, so that the switch has to be custom designed for locks having bolts or bars of different sizes, which traverse paths of different lengths.